This invention relates to sub-miniature connector receptacles in the form of small metal shells which are comparable in size to the stem of a small watch and which are fabricated for incorporation in printed circuit boards, in openings provided therein. More particularly the invention relates to receptacles of this type which incorporate friction contact means adapted to cooperate with contact pins of cooperable male connectors, and incorporate spring-type positioning means engageable with the circuit board to effect the proper orientation of the receptacle.
In the past a number of different kinds of connector receptacles of the above type have been proposed and produced. In general these have all been constituted of tubular metal shells that were either drawn or else rolled, and that were provided at their interiors with spring contactors adapted for engagement with the contact pins of cooperable connectors. The tubular shells were utilized by inserting them in openings of printed circuit boards, where they had a sliding fit. The shell side walls were variously formed, as by embossing, stamping and the like, to effect the retention of the shell body in the board after its insertion. Some cups or shells were knurled for this purpose while others were formed with a non-circular cross section. Various and diverse configurations were devised, effected during the fabrication of the metal into the shell or cup form or else thereafter, all to the end that the shell body would be retained in the circuit board after being initially inserted.
A previous construction was characterized by an inner spring contactor having resilient fingers which were folded down alongside the outside of the shell or cup, so as to yieldably engage the edge surfaces of the opening in the circuit board to accomplish the securement. While this operated fairly well, it had the drawback that, sometimes during the wave soldering operation, the solder would travel along the spring fingers and into the inside of the cup or shell, onto the inner spring contactor. This obviously impaired the resilience of the inner contactor, and in many cases rendered it inoperative.
Because of the very large number of connector receptacles that are being utilized in the large quantities of circuit boards finding use at the present time, an important objective is to bring down the cost of the receptacles to the lowest possible figure, especially in view of the competitive nature of the industry. As a rule, these sub-miniature connector receptacles constitute only a very small percentage of the overall cost of the equipment in which they are used.
Another consideration in the manufacture of sub-miniature connector receptacles of the present type, is that they are required to be held to rather strict tolerances, or else the tolerances of the openings in the circuit boards must be carefully chosen and maintained. This latter was difficult to accomplish, and represented an added cost if insisted on. Because of the tolerance considerations, it was found that many shells or cups would only be loosely held and not sufficiently secure when initially placed in the openings of the circuit boards. In other cases, the shells had too tight a fit whereby difficulty was encountered with their insertion, and as well the likelihood existed that damage could occur to the inner resilient spring means whereby the connector was rendered inoperative. With some tight shells, the fit was so difficult to accomplish that the functioning of the inner spring contactor was wholly impossible. Such would be the case where the openings in the circuit board were too small, even if provision was made in the connector to accommodate a wide range of hole diameters.
The configuration of some prior connector receptacles was such that, unless a very accurate alignment of the receptacle was had with the board opening, interference would be encountered during the inserting movement, resulting in damage or at the very least, slow-down at the inserting operation or station.
It was found in the past that the prior working or forming of the shell wall to effect a retention of the shell body was unacceptable additionally for the reason that it tended to restrict the use of the receptacle so that a universal application was not possible. Moreover, the forming of the shell body into special shapes was not desirable because the cost of the connector would be unacceptable due to the special consideration that had to be given to the shell bodies.